There has been a long standing requirement, virtually throughout industry, for a measuring instrument which is compact and easily usable, and which additionally has the capability of measuring directly a given distance in one measurement language and converting that measurement into another proportional measurement language. Such measurement, for example, may be in the metric system, some other system of measurement, or it may be simply a proportional part of the system within which the original measurement was taken.
This capability has become increasingly important as the drive to convert other systems of measurement to the metric system has gained momentum. Thus, as industry continues to progress in its conversion from one system to another the ability to obtain readings of the nature indicated will become increasingly more significant. Indeed, it is anticipated that a measurement conversion device such as is described and claimed herein will ultimately become a tool which is virtually mandatory for anyone working in the United States measurement system, since it will be necessary to recite such measurements in the metric system. In many instances the reverse will also be true.
Although a considerable amount of work has been accomplished in the general field of measurement conversion, no one has yet provided for the general market a device such as contemplated herein.
Developments such as that described in U.S. Pat. No. 3,801,803 have approached the solution to this problem by providing a system for machine tool equipment in the numerical control field, converting signals from a punched tape in the metric system to the U.S. system. While this approach provided an electronic means to accomplish the conversion, no attempt was made to introduce a complete analog-to-digital system into a compact unit wherein a direct linear measurement, for example, could be immediately translated or converted and displayed as a visual readout in one or more different proportions or different measurement systems, such as is accomplished by the present invention.
Digital systems of the kind represented by U.S. Pat. Nos. 3,780,440, 3,271,564, and 3,526,890 have also approached this system but have been limited in various particulars, particularly in their inability to handle analog information and are, therefore, limited in accuracy to the number of pulses per measurement unit.